[R] The use of F for False and T for True

[Simon Blomberg]

It is better programming practice to use FALSE for false and TRUE for
true, and not F and T. This is because it is quite legal to do this:

T <- FALSE
F <- TRUE

or any other assignment. If you re-assign T or F (which are set to TRUE
and FALSE at the beginning of a session), you run into the sort of
problem that you have discovered.

Also, there is the F and t distributions, and the t() function, so
having variables called F and T may lead to further confusion. If you
mean FALSE, say FALSE. If you mean TRUE, say TRUE. 

Cheers,

Simon.

On Sun, 2008-11-16 at 17:56 -0700, David C. Howell wrote:
> Sampling with and without replacement
> 
> I seem unable to use "replace = F" when I want to sample without 
> replacement. I would think
> that it comes down to "F is not a legitimate abbreviation for FALSE." 
> except that
> Dalgaard (p. 118) uses F for FALSE and it works
>  "pairwise.t.test(folate, ventilation, pool.sd = F)"
> 
> I am having trouble when I try to sample a vector without replacement.
> 
> The following code illustrates my problem.
> 
>  >b <- c(1:8)
> 
>  >sample(b)
> [1] 7 8 3 5 1 6 2 4    # That works correctly--no replacement
>   (This would be my preferred form, but when I look at the code later it 
> is helpful to know
>   explicitly how I did the sampling.)
> 
>  > sample(b, replace = T)
> [1] 7 5 6 2 5 5 4 7    # That is also correct--replacement
> 
>  > sample(b, replace = F)
> [1] 1 7 3 7 3 4 6 5    # There are two 3s and two 7s, so there was 
> replacement
> 
> 
>  >sample(b, replace = FALSE)
> [1] 8 1 3 2 5 6 7 4    # That works just fine
> 
>  >sample(b, replace = "F")
> [1] 5 3 2 8 4 1 7 6     # quoting the F is fine.
> 
> 
> If it is OK to replace TRUE with T, why can't I replace FALSE with F?
> 
>  
>  I have a similar problem if I write data <= read.table(file.choose(), 
> header = F)
>  
>  I'm using a Windows machine with version 2.8.0, but I'm sure that this 
> is not a machine specific problem.
>  Thanks,
>  Dave Howell
> 
-- 
Simon Blomberg, BSc (Hons), PhD, MAppStat. 
Lecturer and Consultant Statistician 
Faculty of Biological and Chemical Sciences 
The University of Queensland 
St. Lucia Queensland 4072 
Australia
Room 320 Goddard Building (8)
T: +61 7 3365 2506
http://www.uq.edu.au/~uqsblomb
email: S.Blomberg1_at_uq.edu.au

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